If its got gypsum in it, you cannot let it come into contact with significant amounts of water because water and gypsum don't mix well.
The house envelope should be complete before installation to avoid water ingress.
I'm wary of this kind of product because the self-levelling screed may not.
Re underfloor heating and self levelled screeds you should ensure that the insulation is turned up at the edges to allow for expansion and prevent thermal loss to structure [particularly on a ground floor with block internal walls.
A crack control joint should be introduced at the door threshold and the pipes in this area are properly sheathed.
Asking about this kind of good practice detail is one way of finding out how good your supplier/installer is.
FWIW
ONQ.